Lowell W . Bradford 1918 - 2007 The

Muzzle flash occurs when the fuel-rich effluent fromthe muzzle of a firearm adequately mixes with oxygen inthe atmosphere and is ignited. The size, character and colorof muzzle flash can vary greatly ranging from virtually novisible light at the muzzle to a very large fireball. The colorcan likewise vary from nearly white to bluish-white to laven-der to orange and red. With some gun-propellant combina-tions, sparks or streamers from burning propellant particlesor primer constituents constitute a noticeable portion of themuzzle flash.The factors dictating the presence or absence of muzzleflash and its character when present include barrel length,propellant type and chemical composition, flame tempera-ture, muzzle pressure, gas volume generated by the propel-lant, exhaust gas products and by-products, projectile type,primer composition and the physical characteristics and be-havior of the propellant grains during the discharge process.The duration of the muzzle flash from a handgun dis-charge can be substantially less than the duration of the nor-mal, involuntary blinking of the eyes consequently a personlooking in the direction of a nighttime gunshot may fail to seethe muzzle flash while one or more other witnesses looking inthe same direction see it without difficulty. IntroductionThe genesis for this work arose from a case in which twoeye witnesses were both looking in the direction of an audiblegunshot but only one of them described seeing a muzzle flash.This disparity in observation became an issue in the case withthe obvious suggestion that one of the witnesses had to be inerror regarding the location of the shooter at the moment ofdischarge.Subsequent testing of the gun and ammunition com-bination revealed that it produced a very noticeable muzzleflash shot after shot. At the time, this writer did nothing be-yond demonstrating this fact using open shutter photographywith a 35mm film camera. This, in part, resulted in an articlepublished in the October 1991 AFTE Journal1. In this method,the camera acts as an accumulator adding up all of the vis-ible light that reaches the camera’s film. In this 1991 article,no time durations for muzzle flashes were provided nor couldthey be provided by the still camera technique. This remainstrue with modern digital cameras. Figure 1 provides an out-standing example of this point. The only source of light inthis photograph taken 20 years ago of the author firing a .44Magnum revolver was that produced by the muzzle flash. Amore recent digital photograph [Figure 2] taken during theOctober 2006 Shooting Scene Reconstruction course by JaneWhitworth shows the discharge of a cap and ball revolverloaded with black powder. Fill flash was also used in thisdigital photograph just prior to the discharge of the .44 caliberrevolver.Olsen and Schneider in their discussion of muzzleflash4,5 also used open shutter photography to capture muzzleflash from a variety of handguns, propellant types and load-ings with each of the guns fired in an unlighted environment.Olsen, however, alludes to the possibility that the duration ofa muzzle flash from a handgun may be shorter than that of ablink of the eyes (page 123, reference 4) but gives no data orreference.More recently one of the authors (Haag) presenteda paper at a combined meeting of the German LKAs (Lan-deskriminalämte) and the BKA (Bundeskriminalamt) held inDresden, Germany that specifically addressed the duration ofmuzzle flashes for some typical handgun cartridges and gunsand compared them to the duration of a typical, involuntaryblinking of the eye lids6. The results presented here are largelyexcerpted from that presentation. Testing Procedures and ResultsThree common pistols (a Ruger, a Beretta and a SIG/Sauer) in 9 mmLuger, .40 S&W; and .45 Automatic respectivelywere each mounted in a Ransom Rest and discharged in asemi-darkened indoor range with various popular brandsof commercial and military ammunition. A variety of 9mmhandloads were also assembled and fired in three makes andmodels of 9mm pistols (Ruger P85, Glock 17, Beretta 92FS)and a Marlin M9 carbine. Many of these shots were record-ed with a Nikon D100 digital camera using the open shuttertechnique. Fill flash was used to record the set up and posi-tion of each pistol just prior to discharge. The setup for this isshown in Figure 3. This technique provided images similarto those in the 1991 AFTE article and allowed the maximumsize of the muzzle flash to be recorded as well as its overallcolor. A Digital8 format Sony Model DRC-TRV350 digital vid-eo-camera was used to record selected shots for subsequentframe-by-frame inspection of the results. At a later date, someshots were recorded in an outdoor environment with a blackdrop cloth positioned just beyond the pistol. This was doneto substantially shorter the shutter speed of the video-cam-era. Vegas 6.0 (Sony Media Software) was used to further re-duce each frame to their respective fields. A video field in theNTSC format represents 1/60 of a second and is one-half of avideo frame.The ability of this video-camera to faithfully recordflashes of very short duration was tested and verified witha General Instruments Model 1538A Stroboscope. The Sonyvideo-camera was aimed directly at the stroboscope from adistance of about 10 feet. The stroboscope had been previ-ously calibrated and set to produce 10 flashes per second ofapproximately two microseconds (0.00002 seconds) durationper flash. When the recorded video was viewed field by field,each stroboscopic flash could be seen in a single field.Additionally, a device called “The Time Machine” (man-ufactured by Mumford Micro Systems) designed to measurethe duration of the flash from photographic flash units, wasused as an alternate means of measuring the duration of themuzzle flash for several selected ammunition types in .45 cal-iber when fired in the SIG/Sauer pistol. [See Table 1]Presented at the Spring 2007 CAC Seminar Anaheim, CA